Temperature measuring system with maximum or minimum selector



y 6, 1943- .1. P. BOSTON TEMPERATURE MEASURING SYSTEM WITH MAXIMUM QRMINIMUM SELECTOR Filed Dec 2. 1944 INVEN TOR.

JOHN P. BOSTON BY ATTORNEY Q2? new. we;

. Patented July 6, 1948 TEMPERATURE MAXIMUM MEASURING SYSTEM WITH ORMINIMUM SELECTOR John P. Boston, United States Navy Application December2, 1944, Serial-No. 566,381

5 Claims.

(Granted under the This invention relates to selecting devices and moreparticularly to an apparatus that selects the maximum or minimumvariations of potential effects, corresponding in magnitude of acondition, of a plurality of sources.

The principal object of this invention'is to provide means for selectingthe maximum or minimum temperature of a plurality of thermal sources.

Another object of this invention is to provide means for selecting,indicating and/r identifying the maximum or'minimum temperature of aplurality of thermal sources.

Another object of this invention is to provide means for selecting,indicating and/or identifying, the maximum or minimum potential effectof a plurality of sources.

Another object of this invention is to provide means for selecting themaximum or minimum potential effect of a plurality of sources.

Anotherobject of this invention is to provide means for selecting themaximum or minimum potential effect from a plurality of sources andapplying said potential effects to control means.

Similar devices. disclosed to date are of a type thatmere'ly indicatesuccessively a series of temperatures of a plurality of sources, butnone disclose automatic means for selecting, indicating, and identifyingthe maximum or minimum temperature of a plurality of sources, asprovided for by this invention, and the application. thereof to acontrol device.

This invention is not limited to thermal indications, but obviously maybe adapted to select maximum or minimum light indications, by merelysubstituting photo-electric generators for the embodied thermo-electricgenerators.

This invention will now be described with reference to the accompanyingdrawing, in which:

Fig. 1 is a wiring diagram in which is embodied several 3-way rotaryswitches diagrammatically. disclosed;

Fig. 2 is a section on switch of Fig. 1;

Fig. 3 is a' section on of Fig; 1; and

Fig. 4 is a section on of 'Fig. 1;

Distributor switch I consists of a stator housing 3 which carries fixedcontacts 5, 3 and 1, circumferentially equally spaced, and a distributorarm 3 rotatively rigid with drive shaft 3 and insulated at 80 therefrom.Fixed contacts 3, 3 and I, are" likewise insulated from line 3-3 ofrotary switch line H of'distributor line 22 of selector act of March 3,1883, as amended April 30, 1928;

housing. Distributor arm 8 successively engages said fixed contacts,thereby making and break ing successively selected relay coil circuits.Element I0 is any means that will transmit current to distributor arm 8such as a brush engaging conductor ring Bl cast integral with arm 8.Shaft 3 is provided with cam II which actuates circuit interrupters l2,l3 and I4, thereby making and breaking successively selected lampcircuits. Rotary switch 2 consists of a non-conducting rotor is withreduced diameter portions l and i6. On the peripheries of said reduceddiameter portions are mounted conductor rings l1 and II, respectively.On the outer periphery of the rotor is are mounted two arcuate shortingbars 10 and 2|. shorting bar is substantially a complete ring except fora gap within which is mounted arcuate shorting bar 2| leaving a smallspace 22 and 23, on each side thereof. Shorting bar 2| is connected toconductor ring l3 through means of conducting element 82. Shorting bar2|! is connected to conductor ring l1 through means of conductingelement 83. Brushes 24 and 25 are suitably mounted and slidingly engagewith conductor rings l1 and I8, respectively. Fixed contacts 28, 21 and28, circumferentially equally spaced, and carried by and insulated fromstator housing 29, slidingly engage shorting bars 20 and 2| andcooperate therewith to make and break selected circuits. The rotor isrotatively rigid with shaft 9 through means of key 84.

Selector switch 3 consists of a non-conducting rotor 30, with reduceddiameter, portions 3! and 32. On the peripheriesof said (reduceddiameter portions 3! and 32 are mounted conductor rings 33 and,respectively. On the outer periphery of the rotor are mounted threerotating contacts 35, 36 and 31, circumferentially equally spaced.Rotating contact 35 is connected to conductor ring 33 through means ofelement 35.

, Rotating contacts 36 and 31 are connected to the stator 38 that atconductor ring 34 through means of elements 33 and 81, respectively.Brushes 38 and 39 are suitably mounted and slidingly engage conductorrings 33 and 34, respectively. Fixed contacts 43, ll. and 42,circumferentially equally spaced, and carried by and insulated fromstator housing 33, slidingly engage rotating contacts 35, 36 and 31 andcooperate therewith to make and break selected circuits. Rotor 30 isrotatively rigid with shaft 3 through means of key 38.

Distributor arm 8, rotor l9, and rotor 30 are all fixed rotatively rigidto drive shaft 3, and are all in phase relationship with each other, sothe instant distributor arm 3 completes circuit through fixed contact 5,rotating contact 2| engages fixed contact 26, and rotating contact 35engages fixed contact 40, simultaneously.

Relay switches 44, 45 and 46, and their associated thermocouples 41, 48and 49, respectively, are connected to switches I, 2 and 3 by circuitsas hereinafter described.

Relay operating coils 50, 5| and 52 are connected in parallel to battery53, with one side of each of said parallel coil branches being completedthrough 3-way distributor switch The function of these circuits isprimarily to energize said relay coils.

The 3-way distributor switch I is shunted through moving contacts 54, 55and 56, with one side of each of said shunts being completed hroughrelay coils 59, 5| and 52, respectively. Shunt contacts 54, 55 and 56are secured to relay moving contacts 69, 6| and 62 of relay switches 44,45 and 46, through insulation means 51, 56 and 59, respectively. As aresult thereof, the shunt contacts 54, 55 and 56, are closedsimultaneously with the relay moving contacts 60, 6| and 62,respectively, and the relays are held closed by these shunt circuitsafter the selector switch arm has left its primary energizing contacts5, 6 and 1, respectively. Said shunts comprise movable contacts 54, 55and 56 and fixed contacts 9|, 94, 96, respectively, circuited acrossdistributor switch I.

Relay operating coils 50, 5| and 52, are shorted-out through selectorswitch 3, with one side of each of said shorting-out circuits beingcompleted through said 3-way selector switch 3. A galvanometer 53 isconnected between selector switch 3 and the relay coils. The function ofthe galvanometer in this circuit is merely to act as a single poledouble throw switch by utilizing the deflection of its needle to make acircuit contact to the left or right. Fixed contacts 19 and 95 coactwith deflecting needle 18 to perform said switching action. Saiddeflection is responsive to the action of the separately energized coilof the galvanometer. These circuits and the hereafter describedthermocouple circuits are completed through the galvanometer andcooperate to effectuate an automatic shorting-out of the relays.

Incandescent identifying lamps 64, 65 and 66, are connected in parallelto relay operating coils 50, 5| and 52, respectively, with one side ofeach of said parallel lamp branches being completed through distributorcircuit breakers 2, l3 and II, respectively. It is understood that anytype of signalling means, other than incandescent lamps, can be used.

The thermocouple circuit consists of thermocouples 41, 46 and 49,connected to the normally open movable contacts, or armatures 14, 60,15, 6|, 16, 62, of relays 44, 45 and 46. Armatures 14, and 16 areconnected to the constantan side of their associated thermocouples; andarmatures 60, 5| and 62 are connected to the iron side of theirassociated thermocouples. Said relays fixed contacts 89, 90, 92, 93, 91,98, with the associated armatures and thermocouples complete a circuitin parallel, for selection purposes, across the temperature indicatingdevice 61, the galvanometer moving coils, and the 3-way rotary switch 2,in series.

Resistors 69, 1| and 13 should be of a magnitude that prevents excessivecurrent from flowing through the deflecting needle contacts 19 and 95.

The minimum temperature may be selected by reversing the connections tothe coils of galvancmeter 63. This is simply reversing the direction ofcurrent flow through thegalvanometer coils for a given temperaturecouple, and the resulting reverse action of the galvanometer needlerejects the relay contacting the higher temperature thermocouple ratherthan that of the lower temperature thermocouple.

Thus far, this disclosure covered a means of selecting and indicatingthe maximum temperature of a number of thermal sources. The same circuitmay be expanded to include temperature control by replacing thetemperature indicating instrument 61 with a maximum-minimum temperaturecontrol instrument as is manufactured by Weston. Such a control devicecould be used to maintain the hottest cylinder of an air-cooled aircraftengine within certain temperature limits by actuating the cowl fiaps.There are, of course, control applications other than for aircraftengines. The principle for other uses would be the same, however, thedetails would be dependent on the method of regulating the flow of thecooling medium.

Operation Any plurality of thermocouplescan be used,

but for purposes of this description three thermocouples will beconsidered. As the distributor arm 8 engages contact 5, for the firstsampling, relay coil 50 becomes energized by battery 53 and actuatesrelay 44 moving contacts 14 and 65 to a closed position with fixedcontacts 69 and 66. The circuit by which relay 44 is actuated to aclosed position is traced as follows: battery 55, element Ill,distributor arm 6, fixed contact 5, resistance 69, relay coil 60, andback to battery 53. When the relay is closed it is held closed after thedistributor arm breaks its primary energizing contact because thedistributor became shunted through movable contact 64 engaging fixedcontact 9| simultaneously with actuation of relay 44. Said shuntcomprises movable contact 54, fixed contact 9|, and resistor 65circuited across distributor switch The circuit by which relay 44 isheld closed is traced as follows: battery 53, movable contact 54, fixedcontact 9|, resistor 69, relay coil 50, and back to battery 53.

Thermocouple-identifying lamp 64 becomes connected in parallel withrelay coil 50 through breaker l2 mounted on distributor switch I. Thisidentifying lamp 54 is lit during the time its associated relay 44 isclosed, except for the small period that the distributor arm 5 iscontacting, at whichtime cam I lifts the breaker l2 and opens saididentifying lamp circuit. (The identifying lamp associated with thehigher thermocouple will remain lighted, while the lower temperaturethermocouples identifying lamp will be rejected immediately upon beingintroduced into the circuit, as will be hereinafter more fullydescribed.)

The closed relay contacts allow the thermocouple 41 current to energizethe temperature indicator 61 and galvanometer 63 circuit through theengagement of rotating contact 2| with fixed contact 26 of rotatingswitch 2.

The temperature indicating instrument 61 remains in circuit with theselected thermocouple 41, after rotating contact 2| breaks with fixedcontact 26, through means of conductor line 11 and the connectedshorting bars l1 and 20 of rotary switch 2, until the next sampling iseffected, except for a negligible period of time represented by gap 22.(The temperature reading I fully explained.)

The moving coil of galvanometer 48 is in circuit with the thermocouplefor onlythe small interval of time that rotating contact 2| issuccessively engaged with fixed contacts 25, 21 and 25. At other timesthe galvanometer coil needle 18 is in a free vertical position ready torespond to the next selective action.

As the distributor arm 5 moves to the next contact for the secondsampling, and engages contact 6, relay coil 5| is also battery energizedand actuates relay 45 moving contacts and I to a closed position withfixed contacts 52 and 55. When relay 45 is closed it is held closed,aiter the distributor arm 8 breaks its primary energizing contact 5,because the distributor- I became shunted through moving contact isengaging fixed contact 94 simultaneously with actuation of relay 45.Said shunt comprises movable contact 55 and fixed contact 54, cirouitedacross distributor switch i. The closing of relay moving contacts'15 and6| connects thermocouple 48 in parallel with thermocouple 41 through theengagement of rotating contact II with fixed contact 21, and allows thethermocouple 48 current to additionally energize the temperatureindicator 81 and galvanometer 63 circuit. The parallel association ofthermocouples 41 and 48 continues for but a very short interval of time,for

ately by the action of galvanometer needle 18 explained in the followingparagraph,

The direction in which the galvanometer needle 18 is deflected dependson which of the selected thermocouples is at the higher temperature.Suppose thermocouple 48 is at the higher temperature, then thegalvanometer needle 18 will move to the left, make contact withgalvanometer fixed contact. 19, and short out the hold-down coil 50 ofrelay 44, through engagement of rotating contact 31 and fixed contact40. Thus relay 45 remains closed and relay 44 is thrown open therebyrejecting thermocouple 41. The temperature-indicating device 61 will nowindicate the temperature of the larger and only remaining thermocouplein circuit with the saidv temperature-indicating device, through meansof conductor line 11, the connected shorting bars l1 and ill, and fixedcontact 21, until the next sampling is eilected. The left or rightthermocouple 45 is the hotter of thepair, its current will dominate thecircuit and be directed through the galvanometer il in a direction that.one or the other is shorted out almost immediwill cause the needle todeflect to the left and reject the lower temperature thermocouple 41from circuit association with said higher temperature thermocouple 48.The remaining thermocouple 48 then bucks thermocouple 45 in the samemanner when the contact 2| moves to contact 28, relay 48 being closed bythe action of rotary switch I. Thermocouple identifying lamp 65 becomesconnected in parallel with relay-coil 5| through breaker 15 mounted ondistributor I. This identifying lamp 65 also became lighted when itsassociated relay 45 was closed, except for the small period of time thatthe distributor arm 8 is contacting at which time cam H lifts thebreaker l3 and opens said identifying lamp circuit. However, one or theother of said lamps will be rejected depending upon which of theirassociated thermocouples is at the lower temperature. This rejection iseflectuated by the galvanometer needle 18 action hereinbefore described,shorting out hold-down coil 50 and its associated identifying-lamp 64.The light circuit is opened during the interval that the distributor iscontacting to prevent extra lighting of a lamp when each relay issampled. The function of the lamp circuit is to identify only thethermocouple that is at the highest temperature. Thus relay 4!; remainsclosed, thermocouple identifying lamp is lighted and the temperatureindicating device 81 will now read the temperature of thermocouple 45,it being the larger temperature of the two thus far sampledthermocouples.

I-Iad thermocouple 41 temperature been greater than thermocouple 45temperature, the galvanometer needle 18 would have been deflected to theright, make contact with galvanometer fixed contact 85, thereby kickingout" relay 45, and consequently thermocouple 48. Consider the part orthe cycle before, during, and after, the selection period whenthermocouple 45 is compared with thermocouple 41. Contact 2| has leftcontact 26 and is approaching contact 21.

the sake of descriptive convenience) of thermocouple 41 is connected tocontact 26, and through rings 20 and I1 to the right terminal ofgalvanometer 65. No current flows through the galvanometer becausecontact 2| is out of the cirdirection in which the galvanometer needle18 the constantan side to the iron side through the hot junction. Thesethermo-electric generators can be incorporated in circuits so that theyeither buck each other or reinforce each other. In this cuit. Meter 61is indicating the temperature of thermocouple 41, connection to theconstantan side being through contact 26, rings 25 and 11, wire 11, andthe wire joining 11 to the right terminal of meter 61. Arm 8 moves on tocontact 5 to close relay '45, and simultaneously, conparticularembodiment, the thermocouples are connected in circuits so that theybuck each other during "the comparing interval. Therefore, since thehottest thermocouplelgenerates the greatest current, and since it bucksthe lesser current from the colder thermocouple, the current from thehottest thermocouple will dominate the circuit, and its direction willdetermine the polarity of the galvanometer 63 coils at any given tact 2iforms an electrical connection with contact 21, which action connectsthe constantan side of thermocouple 48 to the left terminal ofgalvanometer 83 through relay arm 15, relay contact 92, contacts 21 and2|, ring l5, and contact 25. The constantan side of thermocouple 41 isstill connected to the right terminal of galvanometer 53 through wire11, rings i1 and 25, contact 26, and relay 44. Now the energizing coilof galvancmeter 55 has the constantan side of thermocouple 41 connectedto its right terminal and the constantan side of thermocouple 45connectedto its left terminal in bucking relation, since current flowsfrom the constantan side to the iron side through the hot junctions ofboth thermocouples. A current now flows through galvanometer 53, thedirection of which is de:

Relay '44 is closed and the constantan side (so called for termined bywhich thermocouple, 41 or 48, is at the higher temperature. Suppose 48is higher. The polarity of the galvanometer is so arranged that needle18 moves to the left under these circumstances, and relay 44 is openedthrough the action of needle 18 making connection through contacts 18,39, ring 34, contacts 81 and 40 to resistor 89. If thermocouple 41 hadbeen higher, the needle 18 would have moved to the right and shorted.out relay 45, through contacts 88, 38, ring 33, contacts 85 and 4| andresistor 1|. But 48 is the higher, and relay 44 has opened. Now theright terminal of galvanometer 63 is no longer connected to theconstantan side of thermocouple 41, and for a brief instant untilcontact 21 moves away from contact 21, galvanometer O8 is in series withthe constantan sides of thermocouple 48 and that of meter 61 anddeflection of the needle 18 to the left is maintained until 2! leaves21. Themeter 61 takes up the'correct reading of thermocouple 48 whenring 20 moves to contact 21, and maintains it until the next comparisonperiod when thermocouple 48 is introduced into the circuit. When contact2| leaves contact 21, galvanometer 83 is out of the circuit and remainsso until contact 2i touches contact 28.

It should be further understood that coil 50 is not shorted out by theaction of the galvanometer needle 18 when thermocouple 41 is connected.If the instrument is turned on with rotary switches l, 2, and 3 in aposition where relay 44 is the first to be energized, the firsttemperature comparison will be between thermocouple 41 and the coldJunction thermocouple of meter 81. Unless circumstances are veryunusual, thermocouple 41 will be at a temperature higher than that ofthe thermocouple of meter 1. The needle will move to the left (seebelow), and the action will be such as to connect one side of resistors1i and 13 to the battery but with coil 50 not shorted out. Thus relay 44would remain closed until rejected as low in the subsequent normalcomparison periods with thermocouples 48 and 49; The statement that theneedle would be deflected to the left because thermocouple 41 is at ahigher temperature than the thermocouple of meter 61, may appear inconflict with a statement in the preceding description of thespecification, but that it is not the case. In the latter instance, theconstantan side of thermocouple 41 was connected to the right terminalof galvanometer 63 due to the position of switch 2; in other words,contact 26 was bearing on ring 20 since II was contactin 21. It is thepurpose of switch 2 to insert the galvanometer into the circuit so thatthe left terminal always is connected to the constantan side of thethermocouple last brought into the circuit. This is necessary to preventthe action or a higher thermocouple rejecting itself.

As distributor arm 8 moves on fixed contact I. the third sampling relay46 closes, and again the galvanometer needle 18 kicks out" the relayassociated with the lower temperature thermocouple, and so on around torelay 44 again. Thus, only the thermocouple having the maximumtemperature will be finally selected, identified by its associated lamp,and its temperature indicated on the temperature indicating instrument.The operation is continuous and the speed of the cycle depends on thespeed of the driving motor which is limited only by the time required tooperate the relays and galvanometer.

If it should happen that two or more temperatures are the same, andhigher than the remainder oi the temperatures, the galvanometer will notrelease the relays of the two or equal highest thermocouples, and thelamps will indicate this condition by identifying both said sources;

11 a flickering of the needle of the temperature-indicating meter,during the short interval when two thermocouples are being compared, isobjectionable. a mechanical or electrical needle locking device may beused durlng that interval.

11' it is desired to indicate, select, and identify the minimumtemperature, it may be eii'ected by reversingthe connections to thegalvanometer 88 coils. This is simply reversing the direction of currentflow through the galvanometer coils for a given temperature couple, andthe resulting reverse action of the galvanometer needle rejects therelay contacting the higher temperature thermocouple rather than that ofthe lower temperature thermocouple.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is: l

1. An apparatus of the character described, comprising: a source ofcurrent; a plurality of electromagnetically operated switch means; afirst mechanism for successively and individually associating saidsource of current with the electromagnetic operatin means of said switchmeans; means controlled by said switch means when operated forcontinuing said association independent oi' said mechanism; a pluralityoi means for producing electrical efiects respectively correspondingwith variations in magnitudes of a plurality of conditions; common meansfor making measurements of said electrical effects; deflecting meansresponsive to electrical efiects; a second mechanism actingsynchronously with said first mechanism for severally associating saidelectrical effects producing means with said measurement making meansthrough the operated switch means and for associating temporarily two ofsaid electrical effects produoing means in opposition to said deflectinmeans through the operated switch means; and a third mechanism actingsynchronously with said second mechanism during said temporaryassociation for providing short circuits for the operating means of saidtwo switch means then eflective on said effect producing means throughsaid deflecting means in oposite directions, whereby one of the switchmeans will be released depending upon the direction of deflection oi thedeflecting means, and whereby only one of the effect producing meanswill remain in association with the measuring means, and indicatin meansindividual to and controlled by the operative condition of theelectromagnetically operated switch means.

2. The apparatus as set forth in claim 1, in which said means forproducing electrical effects is a thermocouple.

3. The apparatus as set forth in claim 1 in which said deflecting meansis a galvanometer.

4. An apparatus of the character described, comprising: a source ofcurrent; a plurality of electromagnetically operated switch means; afirst mechanism for successively and individually associating saidsource of current with the electromagnetic operating means of saidswitch means; means controlled by said switch means aaeaeai whenoperated for continuing said association independent of said mechanism;a plurality of means for producing electrical eiiects respective lycorresponding with variations in magnitude of a plurality of conditions;common means for making measurements of said electrical efiects;deflecting means responsive to electrical effects; a second mechanismactlngsynchronously with said first mechanism for severally associatingsaid electrical efiects producing means with said measurement makingmeans through the operated switch means and for associating temporarllytwo of said electrical efiects producing means in opposition to saiddeflecting means through the operated switch means; and a thirdmechanism acting synchronously with said secand mechanism during saidtemporary association for providing short circuits for the operatingmeans of said two switch means then effective on said effectproducingmeans through said defleeting means in opposite directions,whereby one of the switch means will bereleased depending upon thedirection of deflection of the deflecting means, and whereby only one ofthe effect producing means will remain in association with the measuringmeans.

5. An apparatus of the character described, comprising: a source ofcurrent; a plurality of electromagnetically operated switch means; afirst mechanism for successively and individually associating saidsource of current with the electromagnetic operating means of saidswitch means; means controlled by said switch means when operated forcontinuing said association independent of said mechanism; a pluralityoi means for producing electrical efiects respectively correspondingwith variations in magnitude of a plurality of conditions; common meansfor making measurements of said elec trical effects; deflecting meansresponsive to electrical effects; a second mechanism actingsynchronously with said first mechanism for severally associating saidelectrical eiiects producing means with said measurement making meansthrough the operated switch means and for associatin temporarily two ofsaid electrical effects producing means in opposition to said defleetingmeans through the operated switch means; and a third mechanism actingsynchronously with said second mechanism during said temporaryassociation for providing short circuits for the operating means of saidtwo switch means then effective on said efiect producing means throughsaid deflecting means in opposite directions, whereby one of the switchmeans will be released depending upon the direction of deflection of thedeflecting means, and whereby only one of the effect producing meanswill remain in association with the measuring means, and indicatingmeans individual to and controlled by the operative condition of theelectromagnetically operated switch means.

JOHN P. BOSTON.

REFERENCE$ CKTED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,496,101 Schmitt June 3, 19241,775,540 Taylor Sept. 9, 1930 2,266,185 Fillo Dec. 16, 1941

